1. Field of the Invention
The present invention relates to a method of testing a distributing cable rigged for electrically connecting a controller (hereinafter referred to as monitored apparatus) which functions for various equipments installed in each vehicle of a railroad train with an electric, diesel or steam locomotive, to a train monitor used for watching and checking such monitored apparatus.
2. Description of the Prior Art
Generally in an electric, diesel or steam railroad train constituted by mutually coupling a plurality of vehicles by means of couplers, it is customary that monitors are provided for monitoring from a motorman's cab or conductor's compartment the operating state of various equipments installed in the vehicles, such as drive means for running the train, brake means for stopping the same, control means (of relatively great importance including hydraulic pump, transmission and so forth) for controlling drivers and actuators for the equipments and, in the case of a passenger train, some auxiliary means such as floodlights, air conditioners, automatic doors and so forth furnished to ensure comfortable ride for passengers. Such monitors and the various monitored apparatus are connected with each other by distributing cables rigged under the floor of each vehicle or on the ceiling thereof. In the prior examples suited to facilitate understanding of the entire constitution of such train monitors, there is known "Train Monitor" disclosed in Japanese Patent Laid-open No. 61 (1986) - 22701 (inventor: Hidehisa Homma).
Conventionally, the distributing cable rigged in each vehicle for the train monitor mentioned above is tested by the use of a tester as shown in FIG. 1, so as to check the presence or absence of any fault or abnormality such as breaking of the cable or electric leakage. First the structure and arrangement of such tester will be described below. A monitor 1 provided for each vehicle and a monitored apparatus 2 to be checked by the monitor 1 are mutually connected by means of a distributing cable 3. The cable 3 is rigged under the floor of each train vehicle or on the ceiling thereof, and a connector 31 to be mated with a connector 11 of the monitor 1 is attached to one end of the distributing cable 3 adjacent to the monitor 1, while a connector 32 to be mated with a connector 21 of the monitored apparatus 2 is attached to another end of the cable 3 adjacent to the monitored apparatus 2. The tester 4 for checking the continuity and so forth of the distributing cable 3 has connectors 41, 42 to which a short testing cable 5 and a long testing cable 6 are connected through connectors 51, 61 attached respectively to ends of the cables 5 and 6 on one side thereof. Meanwhile, to the other ends of the testing cables 5, 6 are attached connectors 52, 62 which are to be mated with connectors 31, 32 attached to the two ends of the distributing cable 3.
The cable 3 rigged between the train monitor of such constitution and the monitored apparatus is tested by the tester 4 in the following procedure.
Normally the monitor 1 and the monitored apparatus 2 are electrically connected to each other through the distributing cable 3, and the operating state of the monitored apparatus 2 is transmitted in the form of electric signals to the monitor 1 so that the apparatus 2 can be checked by the monitor 1.
Since high reliability is required in the distributing cable 3 to ensure the proper function of the monitor 1, a test is conducted when necessary or periodically with respect to the characteristics thereof including electrical continuity. In conducting such a test, first the connectors 31, 32 attached to the two ends of the distributing cable 3 are separated from the connector 11 of the monitor 1 and the connector 21 of the monitored apparatus 2 respectively and, as indicated by dotted-line arrows, the connectors 31, 32 are fitted to connectors 52, 62 respectively at the fore ends of the testing cables 5, 6. Then a signal equivalent to the output of the monitored apparatus 2, e.g. an electric signal equivalent to a braking current in case the monitored apparatus is a brake, is transmitted from the tester 4 and returned thereto via the testing cable 6, the distributing cable 3 and the testing cable 5 as indicated by solid-line arrows. In this stage a display lamp composed of a light emitting diode 43 or the like and disposed in the tester 4 is turned on, blinked or turned off to ascertain the presence or absence of any fault such as breaking of the distributing cable 3.
However, there has been existent the following problem in the above-described conventional method of testing the distributing cable. First, in case the monitor 1 and the monitored apparatus 2 are installed in the front and rear of a single train vehicle, the distributing cable 3 rigged for the monitor 1 becomes considerably long, so that the testing cable 6 also needs to be sufficiently long to meet the requirement, hence raising the installation cost.
Furthermore, due to the necessity of lengthening the testing cable 6 or 5, the work of installing the tester 4 is rendered intricate to eventually cause extreme deterioration of the testing efficiency.
In addition, the longer testing cable 6 or 5 comes to increase the possibility of generating some fault such as breaking of the testing cable itself and, even when any abnormality is found by the tester, it is not obvious whether such abnormality is derived from the distributing cable 3 or the testing cable 6 or 5, thereby impairing the reliability on the test.